The present invention relates generally to subsurface drain systems and the like, and more particularly to a universal drain fitting for prefabricated soil drains.
Civil engineers and architects have long recognized the importance of proper subsurface drainage and providing a subsurface drainage system which allows water to flow freely while soil particles are held in place. While aggregate drain systems, with or without pipes, have been used for centuries, a common problem of this type of drain has been the clogging due to soil infiltration and/or subsidence from soil removal. One conventional approach for providing subsurface drainage is to place perforated pipe, surrounded by select aggregate and geotextile material at a point where drainage is required. While this type of system may be effective, its use is often precluded in all but the most severe conditions due to its high installation costs. An effective, economical alternative to conventional systems are prefabricated geocomposite drainage systems which combine a polymeric core and a geotextile fabric wrap to provide efficient soil filtration, drainage and durability in one prefabricated, easy-to-install package.
Modern prefabricated drains typically consist of 1) a geotextile filter fabric which allows easy water entry while retaining soil particles and 2) a plastic drain core which includes core cones and acts as a collector and transporter of the water. Although some cores are two sided or punched to allow water entry from both sides, most cores are single sided and the typical core thickness is 1/4 inch to 1 inch or 6 to 25 millimeters. In addition, the back of the core may include a thin, high strength polymeric film to prevent soft water-proofing membranes from extruding into the back of the core cones. The prefabricated soil drainage system offers several advantages over other conventional methods for providing subsurface drainage. The prefabricated soil drain is lightweight, economical and easy to install, store and transport. The thickness of the drain requires significantly less space than aggregate drainage. The geotextile fabric permits a high volume of water into the core which has multiple channels for vertical and horizontal water flow, while restraining the soil particles to provide a drain which allows high flow capacity with no clogging. Further, both the core and the geotextile fabric are constructed of materials which are chemically resistant to all naturally-occurring soil materials, and special fabrics and core materials may be used if additional chemical resistance is required.
Prefabricated drains may be grouped into five categories: a sheet drain, a strip drain, a vertical (wick) drain, a highway edge drain and a combination drain. Sheet drains cover an entire surface area and are used where large surface areas require drainage. For example, vertical applications of sheet drains may include basement walls and retaining walls, and horizontal applications may include plaza decks and roof gardens. Strip drains are made in 4 to 36 inch widths and are used where full area coverage is not necessary or practical. The core of a strip drain is usually 1 inch thick and typical applications of the strip drain include golf courses, athletic fields and residential yards. A vertical or wick drain is a special purpose strip drain which is usually 4 inches wide and 1/8 to 1/4 inches thick and used for consolidation of soft, compressible soils. Another special purpose strip drain is a highway edge drain which is usually 12 to 36 inches wide and 1 inch thick and used for highway edge drainage. Another type of strip drain is the combination drain which is made by combining a regular strip drain with a high flow strip drain section. The combination drain is usually 24 inches wide and may be used alone or as the bottom section with a normal sheet drain. Thus, the prefabricated soil drains are designed for a variety of purposes and are available in several different sizes.
In use, a prefabricated soil strip drain is placed in a trench to fit against the side of the trench and extend to the bottom of the trench. The material that was previously removed from the trench is then used to refill the trench and hold the drain in place in the trench. Outlet pipes for carrying the water away from the drain are placed as required by the application and topography. The end of the outlets may direct the water flow to bare ground, concrete drain pads, existing drain boxes or some combination of these. Prior to placing the strip drain in the trench, an outlet connector is installed on the drain for connecting lengths of the strip drain to each other and to the outlet pipes. The connectors must be capable of maintaining the integrity of the system under long-term loads and provide efficient and unrestricted flow while providing a positive connection that will prevent pulling apart during installation procedures. Because the width of the strip drain may typically vary from 4 to 36 inches, it has been necessary to provide a variety of different sizes of connectors to fit the width of the particular strip drain. Thus, a user must have a supply of connectors available for each different size width of strip drain to be installed. Another disadvantage of the current connectors is that the installation of a connector on a non-end portion of the drain requires that the drain be cut in two and that the connector be installed between the two cut portions. If the both portions of the drain are not inserted correctly into the connector, the structural strength of the system and the drain path may be compromised.
In accordance with the present invention, a universal drain fitting device for connecting a prefabricated soil drain to an outlet pipe is provided which is easily and quickly installed on any size drain and at any place on the drain without the risk of harming the structure of the system.